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Aqa chem 4/ chem 5 june 2016 thread

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Predicted grades boundaries? Easy paper, so what's the highest it's ever been for an A and A*? I need an A* to bump up my grade so this is a bit annoying

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Reply 2281

ASLEVELSHELPME

Original post by Charco63

Can't remember exactly but I got something like +2240

Thank god

Reply 2282

openmyeys

Accidentally did MnO4- to Mn3+.... got confused with dichromate, will I lose all the 7 marks?

Reply 2283

Sufyxyz

Original post by Charco63

Can't remember exactly but I got something like +2240

It was 2238

Reply 2284

study2016

Isnt the MnO4:FeC2O4 ratio 3:5?
I used that and ended up getting 53% purity :s-smilie:

Reply 2285

Fibsy

Original post by study2016

Isnt the MnO4:FeC2O4 ratio 3:5?
I used that and ended up getting 53% purity :s-smilie:

Nah 2:5

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Reply 2286

Cadherin

AQA YOU BEAUTIES!!!

I forgive you for CHEM4!! That was such a nice paper. The only bit I didn't get was the 3 marks for the chromium thingy where it went to a solid and gas, damn it!

I'm expecting at least 95 for UMS cap though, so I hope I haven't dropped much more than those 3 marks.

Reply 2287

1010marina

Original post by neevtrehan

How did you do it?

Equation for moles manganate to c2o4-, from what I can remember it was 2:5
Question gave conc and vol of managanate, so multiply for moles, then divide by two times by 5 for c2o4- moles, x10 for volume. Then divide by 3 as the molecule had 3 mols of c2o4-. Find mr (460 something i think?), Find the mass by moles x mr. Then do mass / mass given in the question x100 for percentage

Reply 2288

Cadherin

Original post by openmyeys

Accidentally did MnO4- to Mn3+.... got confused with dichromate, will I lose all the 7 marks?

No way, if you did every other step correctly, you'll probably still get 5.

Reply 2289

Krithika256

Am the only one that found it awful? :frown:

Reply 2290

Cadherin

Original post by Fibsy

Nah 2:5

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Yeah, it's 2:5 and you also have to divide by 3, because 3 molar solution of potassium iron oxalate reacting, to get 94.4%.

Reply 2291

openmyeys

Original post by Fibsy

Predicted grades boundaries? Easy paper, so what's the highest it's ever been for an A and A*? I need an A* to bump up my grade so this is a bit annoying

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The grade Boundaries will be similar to last year, similar paper, with a C2O4- redox titration like last year, so I think it would be 85 for a A* ... and 76/77 for a A, 69 for a B.
They should be higher this year, the paper was not super easy or difficult

Reply 2292

zombaldia

Doesn't get much easier than that

Your right

I used the wrong moles ratio cause I couldn't balance my equation so I ended up with 1:2. But I'm pretty sure I did all the other steps correctly, how many marks do you think I lost?